MOREK, Syria (AP) — A heavily fortified Turkish observation post in the northwestern village of Morek stood surrounded on all sides by Syrian troops Saturday, a testament to the rapid advance of President Bashar Assad’s forces in Syria’s northwest over the past three weeks as rebel defenses collapsed.

Syrian authorities took a group of journalists to tour the observation post, several newly captured villages and the town of Khan Sheikhoun, which was a major rebel stronghold until it was taken by government forces earlier this week.

In Morek, there was no sign of friction between the Turks and the Syrian troops who took positions hundreds of meters away from the observation post. The journalists were kept about 2 kilometers (1.2 mile) away from the Turkish post.

Relations between Turkey and Syria have deteriorated sharply since Syria’s crisis began in 2011, with Damascus accusing Ankara of undermining its security by allowing thousands of foreign fighters to come battle the Syrian army.

Turkey is a strong backer of opposition gunmen fighting Assad’s forces and has 12 observation posts in northwestern Syria as part of an agreement reached last year with Russia, a main backer of the Syrian government.

Farther north, on the road to Khan Sheikhoun, metal black banners could be seen on the roads with signs reading: “Islam is safety,” ″singing is prohibited” and “Islam is the solution.” They appeared to be placed by members of al-Qaida-linked Hayat Tahrir al-Sham, the most powerful group in the northwestern province of Idlib, the last major rebel stronghold in Syria.

In Khan Sheikhoun, despite widespread damage, most of the buildings were standing as it was far from the front lines. Khan Sheikhoun is important as it sits on the highway linking the capital Damascus with the northern city of Aleppo. The link has been cut by rebels since 2012.

One of the main aims of the Syrian army offensive is to open the highway and workers on Saturday were seen paving parts of it in preparation of opening it on the assumption that Syrian troops will capture more areas farther north.

Opposition activists, including the Syrian Observatory for Human Rights, said government forces are now massing troops to push north in their offensive toward the town of Maaret al-Numan, another major town on the highway known as M5.

“The battle was well organized,” a Syrian officer said about their push into Khan Sheikhoun over the past days. “Once we took the hills overlooking Khan Sheikhoun it became easy to take the town.”

During the tour of the town, explosions and heavy machine gun fire could be heard from the distance, while warplanes flew overhead.

Syrian soldier Hussein Hassane, 23, said the battle was difficult in the beginning until the rebels’ defenses collapsed and that’s “when we got the orders to enter Khan Sheikhoun. We moved in and the gunmen were either crushed or fled.”

If Syrian troops keep moving north, there are two other nearby Turkish posts just on the southern edge of Idlib.

The situation in Idlib is expected to be a main topic during a summit between the presidents of Turkey and Russia in Moscow next week.

A Syrian officer in Morek told The Associated Press that Turkish troops and some opposition fighters and their families were inside the sprawling observation post that is surrounded by blast walls.

Assad adviser Bouthaina Shaaban told the Lebanon-based Al-Mayadeen TV that the Turkish base in Morek is under siege, adding that the “Syrian army, God willing, will be able to remove all Turkish posts and terrorists.”

The village itself has suffered massive destruction, in which entire buildings were knocked out and only Syrian troops were seen inside as many of its residents fled since the Syrian army began its last offensive on April 30, forcing more than half a million people to leave their homes.